in last time comes more whdloadgames with MT-32 support.
Manualy change works
Must i always change the option in IO Port - OUT to "MT-32 Synth Emulator" manualy in WinUAE or is there an option to set the IO Port to MT-32 in GameBase to say this WinUAE.
Then starts WinUAE with MT-32 option and run the game.

I have test it with
----
win32.midiout_device=1
win32.midiin_device=-1
win32.midiout_device_name=MT-32 Synth Emulator
----
in GameBase - WHDLoad "GEMUS-Fields" under "Set GEMUS Script Fields" in "Keys and Values" and also in GameBase - Edit - GEMUS "key=value" pairs... for this game in "Edit Current Game Only"